1. Field of the Invention
The present invention relates to a projection image display device operated by a remote controller (referred to as a xe2x80x9cremote control transmitterxe2x80x9d, hereinafter). More particularly, the invention relates to a projection image display device capable of controlling a plurality of projection image displays by one remote control transmitter, and a projection image display device provided with a plurality of remote control signal receiving sections.
2. Description of the Prior Art
In exhibitions, training courses, and so on, projection image displays are used to project images on large screens. In particular, a projection image display called a liquid crystal projector is widely used as it is easily connected to a computer, VTR or the like.
The liquid crystal projector comprises a liquid crystal panel for generating an image according to a signal outputted from the computer, VTR or the like, and an optical engine for projecting the image generated by the liquid crystal panel on the screen in an enlarged manner.
FIG. 1 shows in outline an optical engine of a liquid crystal projector. A light source 50 is, for instance a metal halide lamp, and a dichroic ref lector 51 is arranged around this light source 50. The dichroic reflector 51 orients a light emitted from the light source 50 in one direction. In the front side of a travelling direction of the light emitted from the light source 50, a reflection mirror 52a is arranged at an angle of 45xc2x0 to an optical axis. A UV (ultraviolet-ray)/IR (infrared-ray) cut filter 53 is arranged in the front side of an travelling direction of the light reflected by the reflection mirror 52a. Further down the front side from the cut filter 53, a dichroic mirror 54a for separating a blue light (B), a dichroic mirror 54b for separating a green light (G) and a reflection mirror 52c are arranged all at angles of 45xc2x0 to the optical axis. A reflection mirror 52b is arranged above the dichroic mirror 54a; a dichroic mirror 54c above the dichroic mirror 54b; and a dichroic mirror 54d above the reflection mirror 52c. The reflection mirror 52b and the dichroic mirrors 54c and 54d are respectively arranged in parallel with the dichroic mirrors 54a and 54b and the reflection mirror 52c. Also, a projection lens 57 is arranged in a side direction of the dichroic mirror 54d. 
A capacitor lens 55a and a liquid crystal panel 56a for a blue image are arranged between the reflection mirror 52b and the dichroic mirror 54c. A capacitor lens 55b and a liquid crystal panel 56b for a green image are arranged between the dichroic mirrors 54b and 54c, and a capacitor lens 55c and a liquid crystal panel 56c for a red image are arranged between the dichroic mirror 54b and the reflection mirror 52c. Each of the liquid crystal panels 56a to 56c has a structure, which is built by sealing in a liquid crystal between two transparent substrates: one transparent substrate including a plurality of pixel electrodes arranged in a matrix form, and the other including counter electrodes arranged oppositely to the pixel electrodes. By controlling a voltage applied between the pixel electrode and the counter electrode for each pixel, a transmitted light quantity is adjusted for each pixel to generate an image.
With the liquid crystal projector constructed in the above manner, a light emitted from the light source 50 is reflected on the reflection mirror 52a, and ultraviolet and infrared rays are removed from the light while passing through the filter 53. Then, the light passed through the filter 53 is separated by the dichroic mirror 54a into a blue light (B) to be reflected on the mirror 54a and a light to transmit through the mirror 54a. The light reflected on the mirror 54a is further reflected on the reflection mirror 52b, and passes through the capacitor lens 55a to reach the liquid crystal panel 56a. Then, a transmittance of the blue light (B) is controlled for each pixel by means of an image signal supplied to the liquid crystal panel 56a, and a blue image is generated.
On the other hand, the light transmitted through the dichroic mirror 54a is separated by the dichroic mirror 54b into a green light (G) to be reflected on the dichroic mirror 54b and a red light (R) to transmit through the same. The green light (G) obtained by separation performed by the dichroic mirror 54b passes through the capacitor lens 55b to reach the liquid crystal panel 56b. Then, a transmittance of the green light (G) is controlled for each pixel by means of an image signal supplied to the liquid crystal panel 56b, and a green image is generated. Likewise, the red light (R) transmitted through the dichroic mirror 54b passes through the capacitor lens 55c to reach the liquid crystal panel 56c, and a red image is generated by means of an image signal supplied to the liquid crystal panel 56c. The blue image generated by the liquid crystal panel 56a transmits through the dichroic mirror 54c. By the dichroic mirror 54c, the blue image is synthesized with the green image generated by the liquid crystal panel 56b. Then, by the dichroic mirror 54d, the synthesized image is further synthesized with the red image generated by the liquid crystal panel 56c. The image synthesized in this manner is then projected through the projection lens 57 on the screen.
Usually, the liquid crystal projector can be remotely controlled on its operations including input signal switching, brightness adjustment, contrast adjustment, zooming, focusing, lamp turning ON/OFF, and so on, and operations regarding voices (volume adjustment or the like) by using a remote control transmitter.
FIG. 2 is a block diagram showing an electric circuitry of a conventional liquid crystal projector. A video signal and a synchronizing signal outputted from a computer or a video device enter a liquid crystal driving circuit 62. The liquid crystal driving circuit 62 separates the video signal into an R signal for a red image, a G signal for a green signal and a B signal for a blue image. The driving circuit 62 supplies these R, G and B signals respectively to a liquid crystal panel (R panel) 63a for a red image, a liquid crystal panel (G panel) 63b for a green image and a liquid crystal panel (B panel) 63c for a blue image together with the synchronizing signal.
A control unit 61 sends a signal specifying a display starting position and a signal specifying resolution to the liquid crystal driving circuit 62. The control unit 61 controls a digital/analog converter (abbreviated to xe2x80x9cDACxe2x80x9d, hereinafter) 64, and changes brightness and contrast. In addition, the control unit 61 also controls a character generator 65, and displays a menu screen, a setting screen or the like by the liquid crystal driving circuit 62. In addition, the control unit 61 controls a cooling fan 71 by a fan driving circuit 70.
An operation panel 72 includes various operation buttons provided to be operated by a user. An IR receiving section 73 receives infrared rays transmitted from a remote control transmitter (not shown), and outputs a signal to the control unit 61. Upon having received the signal from the IR receiving section 73, the control unit 61 analyzes the signal, and controls each section according to the analyzing result.
FIG. 3 is a flowchart showing processing performed by the control unit 61 at the time of receiving a remote control signal.
In step S51, the control unit 61 monitors the presence or absence of a signal from the IR receiving section 73. Upon having received a signal from the IR receiving section 73, the process moves to step S52, where analysis of a code of the received signal starts. Then, in step S53, determination is made as to whether the code is normal or not. If it is determined that the code is not normal, then, the process ignores the received signal and returns to step S51, where the control unit 61 continues monitoring the presence or absence of a signal from IR receiving section 73.
On the other hand, in step S53, if it is determined that the code of the received signal is normal, the process moves to step S54 where processing is executed according to a command contained in the received signal.
The inventors consider that problems described below are inherent in the conventional liquid crystal projector. Specifically, in exhibitions, training courses, and so on, a plurality of liquid crystal projectors are simultaneously used most often than not. In such a case, if image focus, brightness or contrast is adjusted by the remote control transmitter, the plurality of projectors will be simultaneously actuated, and adjustment of only a desired projector will be impossible. Accordingly, complex treatments must be carried out. For example, the operation by the remote control transmitter must be canceled to perform adjustment by using an operation, panel of the projector main body. Alternatively, to prevent infrared rays from reaching the other projectors, for example, the IR receiving sections of the other projectors must be covered with paper or the like.
Instead of the infrared-ray remote control transmitter (cordless remote controller), a wire remote controller may be used. However, in the case of the wire remote controller, the same number of remote controllers as that of projectors must be prepared. Considering operability, the use of the wire remote controller will not be practical. A computer or the like may be used to operate the plurality of projectors by one wire remote controller. But the computer must be installed in addition to the projectors, and thus the use of the computer will not be practical, either.
In the case of a projection image display of a type attached to a ceiling, assuming that remote control signal receiving sections are provided in the front and rear sides of the display, an fluorescent lamp if located in the vicinity of one remote control signal receiving section may cause an erroneous operation. This is because the remote control signal receiving section receives noises generated from the fluorescent lamp.
The present invention was made with the above-described problems in mind, and it is an object of the present invention is to provide a projection image display device comprising a plurality of remote control signal receiving sections and capable of preventing an erroneous operation caused by noises generated from a fluorescent lamp or the like.
As illustrated in FIGS. 1 and 6, a projection image display device of the present invention comprises: image generators 13a, 13b and 13c (equivalent to 56a, 56b and 56c in FIG. 1), each means being for generating an image according to a video signal; an image projector (57 in FIG. 1) for projecting the image generated by each of the image generators 13a, 13b and 13c; image adjusting circuits 16 and 17, each means being for adjusting the image projected on the screen; a plurality of remote control signal receivers 26 and 28 for receiving remote control signals outputted from a remote control transmitter; and a control circuit 11 for monitoring outputs of the plurality of remote control signal receivers 26 and 28, controlling each of the image adjusting circuits 16 and 17 according to a normal remote control signal, the remote control signal having been received any one of the remote control signal receivers 26 and 28, and ignoring a signal received by the other of the remote control signal receivers 26 or 28 at least for a specified period of time until the control of each of the image adjusting circuits 16 and 17 according to the received remote control signal is completed.
An object of the present invention is to prevent erroneous operations. This object is basically achieved in the following manner. After a normal remote control signal is received by one remote control signal receiver, signal received by the other remote control signal receiver is ignored at least until image adjustment according to the normal remote control signal is finished. Thus, for example, when noises are superimposed on an output of the other remote control signal receiver, the output of the same is ignored.